What you see in these images is the result of an 8.5 minute roast (in a west bend hot air popper) of a Sumatra Mandheling. The green is only about 1 month old from my supplier, presumably less than 6 months old from the farm. From this coffee I have successfully roasted two batches to just past second crack with almost professional results, this batch is another story...

You can see it is very uneven, many beans look spotted, burnt on one side, and raw on the other. There is a good amount of chaff still on the beans, and overall I would say it doesn't look as dark as it should for 8.5minutes. In the past I have only needed 7.5 minutes to be well into second crack, this batch waited until about then to start.

Opinions?

I'm rather new to this and I really would like to see where I can improve. In a couple of days I will give this batch a grind and see how it tastes, that is after all the deciding measure of quality in my book. But from the looks of things I cant say I have high hopes.

The past few weeks have seen large variations in ambient temperature and humidity, could this have been a cause?

What you see in these images is the result of an 8.5 minute roast (in a west bend hot air popper) of a Sumatra Mandheling. The green is only about 1 month old from my supplier, presumably less than 6 months old from the farm. From this coffee I have successfully roasted two batches to just past second crack with almost professional results, this batch is another story...

You can see it is very uneven, many beans look spotted, burnt on one side, and raw on the other. There is a good amount of chaff still on the beans, and overall I would say it doesn't look as dark as it should for 8.5minutes. In the past I have only needed 7.5 minutes to be well into second crack, this batch waited until about then to start.

Opinions?

I'm rather new to this and I really would like to see where I can improve. In a couple of days I will give this batch a grind and see how it tastes, that is after all the deciding measure of quality in my book. But from the looks of things I cant say I have high hopes.

The past few weeks have seen large variations in ambient temperature and humidity, could this have been a cause?

So it is taking longer for a roast? How well are the heating elements in the popper working?

Len

"Coffee leads men to trifle away their time, scald their chops, and spend their money, all for a little base, black, thick, nasty, bitter, stinking nauseous puddle water." ~The Women's Petition Against Coffee, 1674

I'm not familiar with the popcorn poppers, but since my I-Roast roasts in a similar manner, I'd consider the bean load to start. If you overload the popper and reduce circulation, that could be a cause for such an uneven roast. Another possibility is low voltage when the machine is on. That heating element takes a lot of watts and if the circuit has too much voltage drop, the fan won't be able to provide enough circulation because it's running too slow. The last thing that comes to mind is heat loss from the bean mass during roasting. If too much heat escapes out the top of the popper, then your beans won't reach crack point at the same approximate time. If you've covered the top of the popper too tightly to reduce heat loss, that could also be an issue. The I-Roast uses a fine mesh screen to reduce exhaust particles. If the screen isn't kept clean, pressure builds up in the roast chamber and bean don't circulate as well as they should, so consider that effect with your popper.

About how many pre-roasted grams or ounces are we looking at in your images?

How would I best shield myself from this ambient temperature effect in the future?

Snaxx Said:

I'm not familiar with the popcorn poppers, but since my I-Roast roasts in a similar manner, I'd consider the bean load to start. If you overload the popper and reduce circulation, that could be a cause for such an uneven roast. Another possibility is low voltage when the machine is on. That heating element takes a lot of watts and if the circuit has too much voltage drop, the fan won't be able to provide enough circulation because it's running too slow. The last thing that comes to mind is heat loss from the bean mass during roasting. If too much heat escapes out the top of the popper, then your beans won't reach crack point at the same approximate time. If you've covered the top of the popper too tightly to reduce heat loss, that could also be an issue. The I-Roast uses a fine mesh screen to reduce exhaust particles. If the screen isn't kept clean, pressure builds up in the roast chamber and bean don't circulate as well as they should, so consider that effect with your popper.

About how many pre-roasted grams or ounces are we looking at in your images?

I have been roasting 100g from the beginning, but I did notice less than normal circulation in the first 3 minutes. Would you say the iRoast is a worthy investment over a popcorn popper? Or should I just hold out until Im more comfortable investing in a small drum?

If you're not getting much bean movement (which is borne out by the unevenness of the roast) you could try using fewer beans or stirring them with a wooden stick until they dry out sufficiently so that they can move on their own. It sounds odd, but using a smaller batch can also extend the roasting time.

Most people split the fan and heater circuits. It's not hard to do if you're comfortable with electrics and gives you greater flexibility.

If you're not getting much bean movement (which is borne out by the unevenness of the roast) you could try using fewer beans or stirring them with a wooden stick until they dry out sufficiently so that they can move on their own. It sounds odd, but using a smaller batch can also extend the roasting time.

Most people split the fan and heater circuits. It's not hard to do if you're comfortable with electrics and gives you greater flexibility.

I'd agree with the comments about bean agitation. They look similar to when I overload my BMHG and I get stratified agitation (heat the top layer of the beans, the bottom only gets conduction heat, like too many jeans in a topload washer).

I am no professional roaster by any stretch of the imagination but I have had wonderful results using a BMHG. Total investment was about $40.00 and I roast 455 gram loads. Just my two cents but I would try this method before buying an iRoast.

I started with a FreshRoast ... built a StirCrazy/Turbo Oven and was really disappointed in that (just didn't move the beans evenly enough)

I may have gotten lucky with the particular Bread Machine I used - but it easily does 500grams and probably more - I am getting fantastic roasts with it and it is so easy to control the profile. My roasts are always even --- and no more divots in my beans. I couldn't ask for a better system. (well .. it would be nice if I could pull a lever and eject the beans - but otherwise, it's pretty near perfect for my needs)

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